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 > *UPDATE* problem solved!! Coolant temp on hills GMC 3500

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NTORACN

Moreno Valley

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Posted: 08/14/13 01:57pm Link  |  Quote  |  Print  |  Notify Moderator

Hello everyone, just a quick update on how I fixed my2006 Tioga 24D on a 2005 GMC 3500 chassis from running to hot on long grades. My original post is below. I found that my problem was caused by several things related to my cooling system. Those 3 items were the fan clutch, thermostat and radiator cab. The radiator cap wasn’t able to build enough cooling system pressure (less than 5 psi), the thermostat was a little late in its opening temperature (195 degrees versus its 187 degree rating) and I think the biggest problem area was, the fan clutch never engaged even at 237 degree water temp. I installed a new 180 degree thermostat, a new 15lb radiator cap and a new Hayden (part#2786) severe duty fan clutch. The total cost of parts was $120.

On my test drive earlier today, pulling my same boat up the Cajon Pass with the dash A/C on max and generous amounts of throttle angle to work it a hard as possible, the highest temp on my Scangauge (and the dash gauge) was 207 degrees. The fan clutch only fully engaged once for 40 to 50 seconds during the whole trip and the temp came right back to 200 degrees while I was still climbing the grade and then the fan clutch disengaged. The normal operating temp on anything but long grades is the same 197 to 198 degrees as it was before.

Now I feel completely comfortable that anyone could hop in my motorhome and drive it even in Death Valley in August without it running excessively hot. So for anyone who is tolerating a motorhome that’s running hot, it’s not normal and it can be fixed. I hope this information is useful to someone out there in internet land.

By the way, I stopped by the truck scales on my way home to see what my motorhome and boat weigh. My 2006 Tioga 24D full of gas and water and me in the drivers seat, but no food or other passengers weighed in at 10,920 lbs (3320 lbs on the front axle and 7,600 lbs on the rear axle). My boat weighed in at 3,100 lbs. That brings my grand total weight minus food and 3 passengers to 14,020 lbs, well within spec.

(original post goes from here down)

Hi everybody,

I really like the 24D motorhome with the 6.0L gas and 4L80E trans. On both trips I took with the motorhome while pulling my boat, my motorhome temp gauge and scan gauge both read as high as 235 degree coolant temps on long hard climbs only. All other times it runs 197 to 205 coolant temps. It never boiled over, but runs to hot for my liking. My E350 5.4L Ford never got over 225 degrees on the same grades pulling the same boat. I put a new A/C DElco fan clutch in it and cleaned the debris out of the radiator and A/C condensor. My question for those GMC chassis owners is, how hot has/does your motorhome run on long hard climbs? My local GM dealer is telling me this is NOT normal. I wanted to hear from other GM chassis owners with the 6.0L gas engine, to see what your working temp is.

Thank You in advance.

Randy

* This post was edited 08/31/13 03:21pm by NTORACN *





ericsmith32

Kansas City, KS

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Posted: 08/14/13 02:04pm Link  |  Quote  |  Print  |  Notify Moderator

I've seen ours as high was 220 but that was with slow hill climbs and reserving up the hills. On the highway/ moving in general it tends to stay around 195-197. What coolant ratio and how long has it been since a flush? I haven't did ours yet will next year.


2005 Jayco Escapade 28ZSLP (3500 Chevy chassis)


the bear II

Torrance CA.

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Posted: 08/14/13 02:29pm Link  |  Quote  |  Print  |  Notify Moderator

Check the accuracy of your guage. On my Chevy 3500 the guage read 20° hotter than the coolant actually was. I bought a good after market guage and it confirmed the problem.

Also add Royal Purple "Wetter Water" it's a great product and will help kepp your temps lower. It dropped mine by 20° on 6% grades.

carringb

Corvallis, OR

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Posted: 08/14/13 03:14pm Link  |  Quote  |  Print  |  Notify Moderator

Is it possible you are heavier than you realized? If its the 3500 chassis your coach was built on, GCWR should be 16,000 pounds. How heavy is your boat? I could see your coach easily topping 12k when its loaded.


2000 Ford E450 V10 VAN! 450,000+ miles
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GeoBoy

Bennington

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Posted: 08/14/13 03:38pm Link  |  Quote  |  Print  |  Notify Moderator

I installed a Tru-Cool 40K transmission cooler on my 3500 and it relieves the radiator of the transmission heat load. Now the engine and transmission run cooler. Bought the transmission cooler from Oregon Performance transmissions.

time2roll

Southern California

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Posted: 08/14/13 03:57pm Link  |  Quote  |  Print  |  Notify Moderator

Should not boil until 265 so I would be Ok with it.
What speed, rpm, outdoor temp?


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snowdance

State of Jefferson

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Posted: 08/14/13 05:03pm Link  |  Quote  |  Print  |  Notify Moderator

I have seen a temp near that on my Chevy a few times. But in temps well over 100 degrees and pulling 6-10 percent grades for over 5 miles with the truck AC on. Turn off the AC and it will run cooler. But I just drop a gear and not work it as hard. To hot out there for me to turn the AC off. My 7.4 engine will run 60 mph in 2nd so running 35-45 in 2nd is not a big deal..


Snowdance

We spent most of our money traveling... Just wasted the rest..

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NTORACN

Moreno Valley

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Posted: 08/14/13 06:21pm Link  |  Quote  |  Print  |  Notify Moderator

[image]
This is the gauge at the top of the bishop grade at 68 degrees outside. My scan gauge said 234 degrees just a few minutes earlier. Not sure if the temp would have gone higher had I kept it wide open.

scroller95969

Paradise,CA

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Posted: 08/14/13 06:30pm Link  |  Quote  |  Print  |  Notify Moderator

My 6.0 runs hot also pulling medium to long grades. I have to drop at least 1 gear and keep the revs up just to keep it below 225º pulling a 6% grade on a 85-90º day. It's frustrating because the engine has plenty of power but the cooling system doesn't seem to be able to handle it. I sure would like to be able to solve this problem. I have cleaned the outside of the radiator, drained and flushed the radiator, replaced the cooling fan clutch, replaced the thermostat and changed the radiator cap. I even bought an external water sprayer for the radiator but didn't install it because I couldn't figure out where to put the tank. I figured I would just tap into the existing MH water supply instead but haven't got around to it yet. The temperature gauge matches the ultra gauge that I have. I wonder however if the sending unit (if it has one) for the gauge could be wrong which would probably affect the readout on my ultra gauge as well. The fan clutch doesn't turn on until 225-230º and that just seems too hot to me. After it's on I can keep it between 210-225º. I read somewhere that the cheaper fan clutches turn on at a lower temperature and I am considering trying this but it takes quite a while to take everything apart just to get to the fan clutch. By searching the internet I was able to find others with a 6.0 with this problem when towing. We tow a 10' cargo trailer as well. I have posted on several forums but have yet been able to figure it out. If you find something that helps please post it here so I can try it also.

Seeing your above pic that's right about where mine ran pulling the same grade this spring with the outside temp about 65-70º. I have tried to push the engine harder before to see if it would continue to rise and ended up just one mark below the red. So now I just baby it up the hill. On the grapevine going south I know I could pull it at 55mph but have to bring it all the way down to 30MPH to keep it below 225º on an 80-85º day.

* This post was edited 08/14/13 08:13pm by scroller95969 *


Jeff & Lori
2004 Fleetwood Tioga 22B - Chevy chassis
10' Wells cargo trailer
Gracie Mae - our 9 year old Papillon

IAMICHABOD

Sunny So Cal

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Posted: 08/14/13 07:41pm Link  |  Quote  |  Print  |  Notify Moderator

NTORACN I know we have talked about this before, and mine did the same on a short steep grade.

Did you have the Tow/Haul button, ya know that little button on the dash, engaged? I cannot see it lit on your picture of the dash. I have read on a Chevy forum that when it is engaged while towing or climbing it changes the shift points and keeps the trans cooler thus helping with overall cooling. That I all I got.[emoticon]


2006 TIOGA 26Q CHEVY 6.0 WORKHORSE VORTEC
Former El Monte RV Rental

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